Energy-absorbing anti-collision material and preparation method thereof

Abstract

The invention belongs to the technical field of battery protection, and particularly relates to an energy-absorbing anti-collision material and a preparation method thereof. The energy-absorbing anti-collision material comprises an energy-absorbing layer and a layer plate which are sequentially stacked, the energy-absorbing layer comprises a polyurethane energy-absorbing layer, and preparation raw materials of the polyurethane energy-absorbing layer comprise a premix and a curing agent; the premix comprises polyether glycol, polyether polyol, a chain extender, a cross-linking agent, a filler, a coupling agent, a foaming agent, an emulsifier and a catalyst; the curing agent comprises diisocyanate; the molar ratio of hydroxyl groups in the premix to isocyanate groups in the curing agent is 1: (1-1.1). According to the invention, the energy absorption layer and the laminate are compounded, and the energy absorption layer comprises the non-Newtonian fluid shear thickening composite material and can absorb and disperse impact force, so that the overall anti-collision performance of the battery chassis is improved, and the service life of the battery is prolonged; and the density is small and the weight is light.

Description

Technical Field

[0001] The invention belongs to the technical field of battery protection, and in particular relates to an energy-absorbing and anti-collision material and a preparation method thereof. Background Art

[0002] At present, the battery packs of new energy vehicles are generally protected by metal plate chassis or equipped with bottom protection beams. The protection beams are mostly made of high-strength steel and are set at a position lower than the battery pack. The design of the protection beams is too close to the ground, which may make it easier for the battery pack to be impacted and affect the car's wading ability. Metal plates are generally compounded by a layer of aviation aluminum alloy plate and a layer of steel plate. Although they have certain strength and hardness, they do not have the performance of buffering, energy absorption and shock absorption. When the car is driving, fast-flying stones and other impact objects can easily cause the aluminum alloy or steel to be greatly deformed or punctured after being stressed, causing damage to the lithium battery or even malfunctioning.

[0003] Some cars are equipped with energy-absorbing devices (energy-absorbing layers or energy-absorbing boxes, etc.), or use high-strength protective layers such as composite materials to make protective covers to reduce the impact of collisions on battery packs. However, the energy-absorbing performance is poor, and a large deformation will occur after the impact, which can easily impact the battery pack and damage it. The current battery chassis materials cannot well protect or ensure the normal operation of lithium batteries, resulting in frequent failures of current battery packs after impact. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide an energy-absorbing and anti-collision material and a preparation method thereof. The energy-absorbing and anti-collision material of the present invention has a good energy-absorbing and anti-collision effect, can reduce damage to the battery pack, and ensure the normal operation of the battery.

[0005] The present invention provides an energy absorbing and anti-collision material, comprising an energy absorbing layer and a layer plate stacked in sequence; The energy absorbing layer comprises a polyurethane energy absorbing layer, and the raw materials for preparing the polyurethane energy absorbing layer comprise a premix and a curing agent; The premix comprises the following components in parts by weight: 20-70 parts of polyether diol, 30-80 parts of polyether polyol, 1-20 parts of chain extender, 0.5-3 parts of cross-linking agent, 5-50 parts of filler, 0.5-5.0 parts of coupling agent, 0.05-15 parts of foaming agent, 0.1-5.0 parts of emulsifier and 0.05-5.0 parts of catalyst; the number of hydroxyl groups of the polyether polyol is more than 3, and the hydroxyl value of the polyether polyol is 22-56 mg KOH / g; The curing agent includes diisocyanate; The molar ratio of the hydroxyl group in the premix to the isocyanate group in the curing agent is 1: 1 to 1.1; The layer plate includes one or more layers of a steel plate, an aluminum alloy plate, an engineering plastic plate and a fiber plate; The method for preparing the energy-absorbing and anti-collision material comprises the following steps: The energy absorbing and anti-collision material is obtained by pouring the raw materials for preparing the polyurethane energy absorbing layer on the layers or between the layers, and performing foaming and cross-linking integrated molding.

[0006] Preferably, the polyurethane energy absorbing layer has a thickness of 1 to 20 mm.

[0007] Preferably, the thickness of the steel plate is 0.5-3 mm.

[0008] Preferably, the thickness of the aluminum alloy plate is 0.5-3 mm.

[0009] Preferably, the material of the fiberboard includes one or more of polyethylene fiber, Kevlar fiber, carbon fiber, basalt fiber and polyester fiber, and the thickness of the fiberboard is 0.5-5 mm.

[0010] Preferably, the material of the engineering plastic plate includes one or more of polyphenylene ether, nylon, microporous foamed polypropylene, polyoxymethylene and polyimide, and the thickness of the engineering plastic plate is 0.5-5 mm.

[0011] Preferably, the polyurethane energy absorbing layer and the layer plate are alternately stacked, and the total number of the alternately stacked layers is 2 to 7 layers.

[0012] Preferably, the energy-absorbing and anti-collision material includes an aluminum alloy plate, a polyurethane energy-absorbing layer and a steel plate stacked in sequence, or includes an aluminum alloy plate, a first polyurethane energy-absorbing layer, a steel plate and a second polyurethane energy-absorbing layer stacked in sequence, or includes an aluminum alloy plate, a first polyurethane energy-absorbing layer, a fiberboard, a second polyurethane energy-absorbing layer and a steel plate stacked in sequence.

[0013] The present invention also provides a method for preparing the energy-absorbing and anti-collision material described in the above technical solution, comprising the following steps: The energy absorbing and anti-collision material is obtained by pouring the raw materials for preparing the polyurethane energy absorbing layer on the layers or between the layers, and performing foaming and cross-linking integrated molding.

[0014] Preferably, the temperature of the foaming and cross-linking integrated molding is 35-80° C. and the time is 2-10 min.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The invention provides an energy absorbing and anti-collision material, comprising an energy absorbing layer and a layer plate which are stacked in sequence; the energy absorbing layer comprises a polyurethane energy absorbing layer, and the raw materials for preparing the polyurethane energy absorbing layer comprise a premix and a curing agent; the premix comprises the following components in parts by weight: 20 to 70 parts of polyether diol, 30 to 80 parts of polyether polyol, 1 to 20 parts of a chain extender, 0.5 to 3 parts of a cross-linking agent, 5 to 50 parts of a filler, 0.5 to 5.0 parts of a coupling agent, 0.05 to 15 parts of a foaming agent, 0.1 to 5.0 parts of an emulsifier and 0.05 to 5.0 parts of a catalyst; the number of hydroxyl groups in the polyether polyol is more than 3, and the hydroxyl value of the polyether polyol is 22 to 56 mg KOH / g; the curing agent comprises a diisocyanate; the molar ratio of the hydroxyl group in the premix to the isocyanate group in the curing agent is 1: 1 to 1.1; the layer plate comprises one or more layers of a steel plate, an aluminum alloy plate, an engineering plastic plate and a fiber plate.

[0016] The energy-absorbing and anti-collision material of the present invention is a composite of an energy-absorbing layer and a layer plate. The energy-absorbing layer includes a non-Newtonian fluid (NNF) shear thickening composite material, which remains soft and has a suitable elastic state under normal conditions. When subjected to rapid and severe impact or extrusion, it can quickly increase strain through local density increase, showing an obvious shear thickening phenomenon, that is, when the material is impacted by an external force, it behaves as a hard solid, and as the external force increases, the strength of the material increases; when the external force disappears, the material will return to its original relaxed soft elastic state, which can effectively absorb and reduce the impact force, and has a good energy absorption effect. The energy-absorbing and anti-collision material of the present invention has good energy-absorbing and anti-collision performance, can absorb and disperse the impact force, can withstand impacts greater than>150 joules, prevent large deformation or breakdown, and can effectively prevent bottoming. The energy-absorbing and anti-collision material of the present invention can reduce the impact force generated by stones or unknown foreign objects in the driving process of electric vehicles, improve the overall anti-collision performance of the battery chassis, and extend the service life of the battery. Moreover, the energy-absorbing and anti-collision material of the present invention has the advantages of low density and light weight.

[0017] Furthermore, the present invention adds a fiber layer to the energy-absorbing and anti-collision material to transform point force into surface force, which is beneficial to further disperse the overall force, improve the overall force-bearing capacity of the material, and better meet the protection requirements of the battery pack.

[0018] The present invention also provides a method for preparing the energy-absorbing and anti-collision material described in the above technical solution, wherein a shear thickening fluid material is poured on or between the layers, and an integrated casting molding technology is adopted to combine a plurality of materials together during the integrated foaming reaction molding. The obtained multi-layer composite structural material has excellent bonding strength, and after being subjected to a large impact (150J), the layers do not crack, and the material has a small deformation, and has strong tear resistance and deformation resistance, thereby ensuring a normal working environment for the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 This is a schematic diagram of the product structure of the lithium battery chassis composite material prepared in Example 1; Figure 2 The results of the 150J impact test of the lithium battery chassis composite material samples of Examples 1 to 3 and the comparative samples; Among them, 1-steel plate, 2-polyurethane energy absorption layer, 3-aluminum alloy plate. DETAILED DESCRIPTION

[0021] The present invention provides an energy absorbing and anti-collision material, comprising an energy absorbing layer and a layer plate stacked in sequence; The energy absorbing layer comprises a polyurethane energy absorbing layer, and the raw materials for preparing the polyurethane energy absorbing layer comprise a premix and a curing agent; The premix comprises the following components in parts by weight: 20-70 parts of polyether diol, 30-80 parts of polyether polyol, 1-20 parts of chain extender, 0.5-3 parts of cross-linking agent, 5-50 parts of filler, 0.5-5.0 parts of coupling agent, 0.05-15 parts of foaming agent, 0.1-5.0 parts of emulsifier and 0.05-5.0 parts of catalyst; the number of hydroxyl groups of the polyether polyol is more than 3, and the hydroxyl value of the polyether polyol is 22-56 mg KOH / g; The curing agent includes diisocyanate; The molar ratio of the hydroxyl group in the premix to the isocyanate group in the curing agent is 1: 1 to 1.1; The layer plate includes one or more layers of a steel plate, an aluminum alloy plate, an engineering plastic plate and a fiber plate; The method for preparing the energy-absorbing and anti-collision material comprises the following steps: The energy absorbing and anti-collision material is obtained by pouring the raw materials for preparing the polyurethane energy absorbing layer on the layers or between the layers, and performing foaming and cross-linking integrated molding.

[0022] In the present invention, unless otherwise specified, the materials and equipment used are commercially available products in the art.

[0023] In the present invention, the thickness of the polyurethane energy absorbing layer is preferably 1-20 mm, specifically 2 mm, 3 mm, 4 mm or 5 mm. The polyurethane energy absorbing layer can absorb and disperse instantaneous impact force.

[0024] In the present invention, the polyether diol preferably includes polyoxypropylene diol and / or polyoxypropylene-ethylene oxide polyether diol. The polyether diol can provide a soft segment chain structure, provide buffering energy absorption, and prevent the instantaneous rebound of the hard segment network.

[0025] In the present invention, the polyether polyol preferably includes one or more of polyoxypropylene polyol, polyoxyethylene polyol, polyoxypropylene-ethylene oxide copolymer polyol and polystyrene-acrylonitrile copolymer polyol. The polyether polyol is preferably a polyether triol, and the polystyrene-acrylonitrile copolymer polyol is preferably polyether polyol 3630. The polyether polyol can provide a network support for the hard segment. When subjected to impact force, the hard segment networks support each other and can quickly assemble, giving the material high impact resistance and high energy absorption characteristics, thereby achieving the effects of damping, energy absorption and vibration reduction.

[0026] In the present invention, the chain extender preferably includes a first chain extender and / or a compound chain extender, and the first chain extender preferably includes one or more of 3-methyl-1,5-pentanediol, 1,4-cyclohexanediol, 4,4'-bis-sec-butylaminodiphenylmethane, methyl propanediol, 1,6-hexanediol, 1,4-bis(2-hydroxyethoxy)benzene, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butanediol, 1,4-butanediol, diethylene glycol, dipropylene glycol, neopentyl glycol and hydroquinone bis(2-hydroxyethyl) ether; the compound chain extender is preferably prepared by chain extension reaction of raw materials including the first chain extender and a chain extension curing agent.

[0027] In the present invention, the cross-linking agent preferably includes an alcoholamine cross-linking agent and / or an alcohol cross-linking agent, the alcoholamine cross-linking agent preferably includes one or more of ethanolamine, diethanolamine and triethanolamine, and the alcohol cross-linking agent preferably includes glycerol. The cross-linking agent can generate chemical bonds between linear molecules, so that the linear molecules are connected to each other to form a network structure, thereby improving the strength and elasticity of the material.

[0028] In the present invention, the filler preferably includes one or more of white carbon black, wollastonite powder, kaolin, silica powder, carbon black and glass fiber. The filler can improve the impact resistance of the material.

[0029] In the present invention, the coupling agent preferably includes an amino-containing silane coupling agent, which can ensure that the filler does not fall off or separate.

[0030] In the present invention, the foaming agent is preferably a physical foaming agent, and the physical foaming agent preferably includes H 2 O, dichloromethane, 1,1,1,3,3-pentafluorobutane and 1,1-dichloro-1-fluoroethane, one or more of the H 2O is preferably deionized water, and the foaming agent plays a foaming role to adjust the molding density of the product.

[0031] In the present invention, the emulsifier preferably includes a polysiloxane-oxyalkylene block copolymer.

[0032] In the present invention, the catalyst preferably includes one or more of dimethylethanolamine, triethylenediamine, 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), N,N-dimethylcyclohexylamine, bis(2-dimethylaminoethyl) ether, N,N,N′,N′-tetramethylalkylenediamine, N,N-dimethylbenzylamine and an organic bismuth catalyst, and the catalyst can adjust the start time, demolding time and post-ripening time of the polymerization reaction.

[0033] In the present invention, the curing agent preferably includes diphenylmethane diisocyanate and / or 1,5-naphthalene diisocyanate.

[0034] In the present invention, the molar ratio of the hydroxyl group in the premix to the isocyanate group in the curing agent is preferably 1:1.02-1.05, specifically 1:1.05.

[0035] In the present invention, the steel plate preferably includes a DP590 steel plate.

[0036] In the present invention, the thickness of the steel plate is preferably 0.5-3 mm, specifically 1 mm, 1.5 mm or 2 mm.

[0037] In the present invention, the aluminum alloy plate preferably includes a 7075 aluminum alloy plate.

[0038] In the present invention, the thickness of the aluminum alloy plate is preferably 0.5-3 mm, specifically 1 mm or 2 mm.

[0039] In the present invention, the material of the fiberboard preferably includes one or more of polyethylene fiber, Kevlar fiber, carbon fiber, basalt fiber and polyester fiber, and the thickness of the fiberboard is preferably 0.5-5 mm, specifically 1 mm, 2 mm or 3 mm. The present invention adds a fiber layer to the energy-absorbing and anti-collision material, and the fiber layer is similar to a net bag, which is conducive to further dispersing the overall force, converting point force into surface force, and improving the overall force-bearing capacity of the material.

[0040] In the present invention, the material of the engineering plastic plate preferably includes one or more of PPO (polyphenylene ether), PA (nylon), MPP (microporous expanded polypropylene), POM (polyoxymethylene) and PI (polyimide), and the thickness of the engineering plastic plate is preferably 0.5-5 mm, specifically 1 mm, 2 mm or 3 mm.

[0041] In the present invention, the polyurethane energy absorbing layer and the layer plate are preferably alternately stacked, and the total number of layers of the alternate stacking is preferably 2 to 7 layers, specifically 3 layers, 4 layers or 5 layers.

[0042] In the present invention, the energy absorbing and anti-collision material preferably includes an aluminum alloy plate, a polyurethane energy absorbing layer and a steel plate stacked in sequence, or includes an aluminum alloy plate, a first polyurethane energy absorbing layer, a steel plate and a second polyurethane energy absorbing layer stacked in sequence, or includes an aluminum alloy plate, a first polyurethane energy absorbing layer, a fiberboard, a second polyurethane energy absorbing layer and a steel plate stacked in sequence. The present invention stacks a fiber layer and a polyurethane energy absorbing layer, which can better prevent a large impact force from penetrating the material while absorbing energy and reducing shock, and meets the requirements of outdoor harsh road conditions.

[0043] In the present invention, the total thickness of the energy-absorbing and anti-collision material is preferably 7-11 mm, specifically 7 mm, 9 mm or 10 mm.

[0044] The present invention also provides a method for preparing the energy-absorbing and anti-collision material described in the above technical solution, comprising the following steps: The raw materials for preparing the polyurethane energy absorbing layer are poured on the laminates or between the laminates, and foaming and cross-linking are performed for integrated molding to obtain the energy absorbing and anti-collision material.

[0045] In the present invention, the method preferably further comprises: mixing the premix and the curing agent at a high speed before pouring, wherein the rotation speed of the high speed mixing is preferably 3000-8000 rpm, more preferably 3500-4000 rpm, and the time is preferably 1-10 s.

[0046] In the present invention, the temperature of the foaming and cross-linking integrated molding is preferably 35-80°C, more preferably 50-70°C, specifically 55°C or 60°C, and the time is preferably 2-10 min, more preferably 7-9 min, specifically 7 min, 8 min or 9 min.

[0047] In the present invention, the raw materials for preparing the pouring energy absorbing layer are preferably prepared in a mold, and the mold is preferably provided with an exhaust channel and has a quick locking function (installing a quick locking clamp); the exhaust channel is preferably located at the uppermost end (highest point) of the mold cavity, and the diameter of the exhaust channel is preferably 0.3 to 3 mm, more preferably 1 mm. The mold preferably further comprises: uniformly spraying a release agent on the surface of the mold cavity before use.

[0048] The present invention preferably places the layer plates in the upper cavity and the lower cavity of the mold respectively, injects the raw materials for preparing the polyurethane energy absorbing layer into the middle, and closes and locks the mold. The polyurethane layer raw materials undergo polymerization reaction in the mold cavity, foam and fill the entire mold cavity, and while the foaming pressure in the mold cavity increases, the air in the mold cavity is discharged through the exhaust hole, and at the same time, the energy absorbing layer is pressed and attached to the surface of the layer plates, and the layer plates and the energy absorbing layer are firmly combined to absorb and disperse the instantaneous impact force.

[0049] In order to further illustrate the present invention, the energy absorbing and anti-collision material and the preparation method thereof provided by the present invention are described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0050] In the embodiment of the present invention, the NNF (non-Newtonian fluid) liquid used includes a premix and a curing agent, and the specific preparation method is as follows: 1) Preparation of compound chain extender: 50g of diethanolamine, 130g of ethylene glycol, 320g of 3-methyl-1,5-pentanediol and 500g of 1,4-butanediol were added in a constant temperature container at 80°C, stirring was started and the stirring speed was maintained at 100rpm, the container was sealed, vacuum dehydration was started, and a negative pressure of -0.1MPa was maintained for 8 hours to obtain the first component. According to the molar ratio of the hydroxyl group in the first component to the isocyanate group in the liquefied modified MDI (WANNATE8001) (100:60), the liquefied MDI was slowly added to carry out polymerization chain extension reaction for 8 hours, the heating and stirring were stopped, and the compound chain extender (NNF-1) was obtained when the material temperature dropped to room temperature.

[0051] 2) Preparation of premix: Add 500 g of 1000 molecular weight polyether diol into a 75°C constant temperature container; start stirring and maintain the speed at 100 rpm, then add 100 g of the NNF-1 compound chain extender described in step 1), silane coupling agent (XIAMETER тм OFS-6020Silane) 20g, polysiloxane-olefin oxide block copolymer emulsifier 10g, nano white carbon black (AEROSIL200) 200g; continue stirring for 45 minutes, stop heating, add polyether diol 200g, polyether triol (350)g, triethanolamine 10g, foaming catalyst dimethylethanolamine 8g and curing catalyst triethylenediamine 5g, continue stirring; when the temperature drops to 30℃, add foaming agent (deionized water) 2.5g; keep stirring for 30 minutes and stop stirring to obtain a premix, and the temperature is controlled at 25℃. The polyether diol is C2010, the polyether triol is 330N and the polyether polyol 3630.

[0052] 3) Preparation of curing agent: According to the molar ratio of hydroxyl group in the premix to isocyanate group in the curing agent of 1:1.05, weigh the liquefied MDI and add it to another container. The temperature is controlled at 35°C.

[0053] The premix and curing agent were mixed at a high speed of 3500 rpm for 10 s before use.

[0054] Example 1 (1) Mold preparation: Prepare the mold, which should have the function of quick locking (install quick locking fixture); open an exhaust channel with a diameter of 1.0 mm at the top (highest point) of the mold cavity; set the mold temperature to 55°C; and evenly spray the release agent on the surface of the mold cavity for later use.

[0055] (2) Cut the DP590 steel plate with a thickness of 1 mm into a size of 10*10 cm and place it in the upper die of the mold. Cut the 7075 aluminum alloy plate with a thickness of 2 mm into a size of 10*10 cm and place it in the lower die of the mold for use.

[0056] (3) In the mold cavity, inject the corresponding amount of NNF liquid (middle layer) according to the volume of the 4 mm energy-absorbing layer after molding, and close and lock the mold.

[0057] (4) Composite one-piece molding: The NNF raw material is cross-linked and cured in the mold cavity, and matured at 60°C for 7 minutes in the mold cavity. As the foaming pressure in the mold cavity increases, the air in the mold cavity is discharged through the exhaust holes, and the NNF energy-absorbing layer is squeezed and bonded to the surface of the steel plate and aluminum alloy plate. The product is taken out of the mold, and the excess scraps are polished off along the periphery to obtain a three-layer composite energy-absorbing and anti-collision lithium battery chassis composite material with a thickness of 7 mm.

[0058] The product structure diagram of the lithium battery chassis composite material prepared in Example 1 is as follows Figure 1 As shown, it includes a steel layer, a non-Newtonian fluid foam layer (NNF energy absorbing layer) and an aluminum alloy layer.

[0059] Example 2 (1) Mold preparation: Prepare the mold, which should have the function of quick locking (install quick locking fixture); open an exhaust channel with a diameter of 1.0 mm at the top (highest point) of the mold cavity; set the mold temperature to 55°C; and evenly spray the release agent on the surface of the mold cavity for later use.

[0060] (2) The three-layer composite material obtained in Example 1 is placed in the lower cavity of the mold with the steel plate surface of the three-layer composite material facing upward, and the corresponding amount of NNF liquid is injected according to the volume of the 3 mm energy absorption layer after molding, and the mold is closed and locked.

[0061] (3) Composite one-piece molding: The NNF raw material is cross-linked and cured in the mold cavity, and matured in the mold cavity for 8 minutes. As the foaming pressure in the mold cavity increases, the air in the mold cavity is discharged through the exhaust hole, and the NNF energy-absorbing layer is squeezed and bonded to the surface of the steel plate. The product is taken out of the mold, and the excess scraps are polished off along the periphery to obtain a four-layer composite energy-absorbing and anti-collision lithium battery chassis composite material with a thickness of 10 mm.

[0062] Example 3 (1) Mold preparation: Prepare the mold, which should have the function of quick locking (install quick locking fixture); open an exhaust channel with a diameter of 1.0 mm at the top (highest point) of the mold cavity; set the mold temperature to 55°C; and evenly spray the release agent on the surface of the mold cavity for later use.

[0063] (2) Cut the 1 mm thick DP590 steel plate into pieces of 10*10 cm in size and place them in the lower cavity of the mold for later use.

[0064] (3) Place a layer of 2 mm thick ultra-high molecular weight polyethylene fiber (PE-UD cloth, J200) in the upper cavity of the mold and set aside.

[0065] (4) Inject the corresponding amount of NNF liquid into the lower cavity according to the volume of the 2 mm energy absorption layer after molding, and close and lock the mold.

[0066] (5) Composite one-piece molding: The NNF raw material is cross-linked and cured in the mold cavity, and matured in the mold cavity for 8 minutes. As the foaming pressure in the mold cavity increases, the air in the mold cavity is discharged through the exhaust hole, and the NNF energy-absorbing layer is also squeezed and bonded to the surface of the steel plate and fiberboard. The mold is opened and the product is taken out. The excess scraps are polished off along the periphery to obtain a composite material of steel plate, NNF energy-absorbing layer and fiber layer.

[0067] (6) Repeat (1) mold preparation.

[0068] (7) The composite fiber layer obtained in (5) is placed upward in the lower cavity of the mold, and a cut 7075 aluminum alloy plate with a thickness of 2 mm and a size of 10*10 cm is placed in the upper cavity of the mold; (8) Inject the prepared NNF raw material into the lower cavity according to the volume of the 3 mm energy absorption layer after molding, and close and lock the mold.

[0069] (9) Composite one-piece molding: The NNF raw material is cross-linked and cured in the mold cavity, and matured in the mold cavity for 9 minutes. As the foaming pressure in the mold cavity increases, the air in the mold cavity is discharged through the exhaust hole, and the NNF energy-absorbing layer is squeezed and bonded to the surface of the steel plate or aluminum alloy plate. The product is taken out of the mold, and the excess scraps are cut off along the periphery with scissors to obtain a five-layer composite energy-absorbing and anti-collision lithium battery chassis composite material with a thickness of 10 mm.

[0070] Test Example 1 The lithium battery chassis composite material samples prepared in Examples 1 to 3 were subjected to a 150J impact test (a 15kg steel ball was dropped from a height of 1 meter, the comparative sample, Examples 1 and 3 first hit the steel plate, and Example 2 first hit the NNF energy absorption layer), and compared with the steel plate and aluminum alloy plate composite material comparative samples of the same size (length × width × height = 10 cm × 10 cm × 3 mm). The results are shown in Tables 1 and Figure 2 As shown: Table 1 150J impact test results

[0071] from Figure 2 It can be seen from the data in Table 1 that after the comparison sample was subjected to a 150J impact, it was severely deformed and close to the bottom. The height of the convex point from the Φ60 ring to the center of the convex point reached 9.65mm, and the lithium battery pack was at risk of being damaged; while the energy-absorbing and anti-collision lithium battery chassis material prepared by Examples 1 to 3 of the present invention, the height of the convex point from the Φ60 ring to the center of the convex point was significantly reduced. When two layers of NNF are used, the convex point height can be reduced to less than 5mm; when two layers of NNF and one layer of fiberboard are used, the convex point height can even be reduced to less than 3mm; in addition, due to the use of reaction composite integrated molding technology, there is no cracking phenomenon between the composite multiple layers, which greatly guarantees the normal operation of the lithium battery pack.

[0072] Test Example 2 1. Select several polymer materials with high hardness and density, such as PPO (polyphenylene ether), PA (nylon), and MPP (microporous foamed polypropylene), and use the NNF raw materials used in the examples to prepare NNF-A and NNF-B energy-absorbing materials with different densities and the same thickness. The samples with the same size (10×10 cm) and thickness (5 mm) are subjected to a 25 J impact test (using a 2.5 kg steel ball dropped from a height of 1 meter). The comparative experimental results are shown in Table 2 below: Table 2 Comparison of energy absorption performance of several polymer materials

[0073] Note: The smaller the sensor value (impact test result), the better the energy absorption and shock absorption performance of the material at the same thickness.

[0074] As can be seen from the data in Table 2, the energy absorption effect of NNF far exceeds that of several polymer materials, in the order of NNF-B > NNF-A > PA > MPP > PPO; at the same time, NNF has an obvious mass advantage, with the mass from small to large being NNF-A < NNF-B < MPP < PA < PPO. The NNF used in the present invention as an energy absorption material has excellent energy absorption and buffering performance, which is 2 to 3 times that of other materials, while the mass is only 1 / 2 to 1 / 3 of other materials.

[0075] 2. Prepare NNF-C material using the following NNF liquid material, including premix and curing agent. The preparation method is as follows: 1) Preparation of compound chain extender: Add successively in a constant temperature container at 80 °C: 50 g of diethanolamine, 130 g of ethylene glycol, 320 g of 3-methyl-1,5-pentanediol, and 500 g of 1,4-butanediol. Start stirring and maintain a stirring speed of 100 rpm. Seal the container, start vacuum dehydration, and maintain a negative pressure of -0.1 MPa for 8 hours to obtain the first component. According to the molar ratio of hydroxyl groups in the first component to isocyanate groups in liquefied MDI of 100:50, slowly add liquefied MDI for polymerization chain extension reaction for 8 hours. Stop heating and stirring. Wait for the material temperature to drop to room temperature to obtain the (NNF-1) compound chain extender.

[0076] 2) Preparation of premix: Add 500 g of polyether diol with a molecular weight of 1000 in a constant temperature container at 75 °C; start stirring and maintain a stirring speed of 100 rpm, then add 100 g of the NNF-1 compound chain extender described in step 1), 20 g of silane coupling agent (XIAMETER тм OFS-6020Silane), 10 g of polyorganosiloxane-oxyalkylene block copolymer emulsifier, and 200 g of nano-silica (AEROSIL200); continue stirring for 45 minutes, stop heating, add 200 g of polyether diol with a molecular weight of 2000, 300 g of polyether triol with a molecular weight of 5000, 10 g of triethanolamine, 8 g of foaming catalyst dimethylethanolamine, and 5 g of curing catalyst triethylenediamine, and continue stirring; when the temperature drops to 30 °C, add 2.5 g of foaming agent (deionized water); keep stirring for 30 minutes and then stop stirring to obtain the premix, with the temperature controlled at 25 °C. The polyether diol is C2010, and the polyether triol is 330N.

[0077] 3) Preparation of curing agent: According to the molar ratio of hydroxyl groups in the premix to isocyanate groups in the curing agent of 1:1.05, calculate and weigh liquefied MDI, add it to another container, and control the temperature at 35 °C.

[0078] Mix the premix and the curing agent at a high speed of 3500 rpm for 10 s and then use.

[0079] 4) Preparation of NNF-C by in-situ integrated reaction molding: Select a mold with a quick locking function (install a quick clamp); open a 1.0mm diameter exhaust channel at the top (highest point) of the mold cavity; control the mold temperature at 50°C; spray a release agent evenly on the surface of the mold cavity for use. Inject the NNF liquid into the lower mold cavity of the mold; cover the upper mold of the mold; and lock and fix the upper and lower molds through a quick locking device to form a complete model cavity. The raw material polymerizes in the mold cavity, starts the molecular chain extension, foaming and filling the entire mold cavity, cross-linking, and curing. The raw material matures and reacts in the mold cavity for 8 minutes, the mold is opened to take out the product, and it is placed in a 34°C environment for 24 hours to obtain a foamed polyurethane material NNF-C with a size of length × width × height (100×100×20mm).

[0080] Similarly, NNF-D was prepared using the NNF liquid used in the example. The hardness test results of NNF-C and NNF-D materials are shown in Table 3: Table 3 Hardness test results

[0081] The NNF liquid used in the embodiment of the present invention increases the proportion of isocyanate groups in the hard segment and the proportion of polyols in the soft segment, and the Shore hardness reaches 75, which can better meet the hardness and bearing capacity requirements of the anti-collision material.

[0082] Although the above-mentioned embodiments have made a detailed description of the present invention, they are only some embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on the embodiments of the present invention without creative work, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. An energy-absorbing and anti-collision material, characterized in that: It includes energy absorbing layers and laminates stacked in sequence; The energy absorbing layer comprises a polyurethane energy absorbing layer, and the raw materials for preparing the polyurethane energy absorbing layer comprise a premix and a curing agent; The premix comprises the following components in parts by weight: 20-70 parts of polyether diol, 30-80 parts of polyether polyol, 1-20 parts of chain extender, 0.5-3 parts of cross-linking agent, 5-50 parts of filler, 0.5-5.0 parts of coupling agent, 0.05-15 parts of foaming agent, 0.1-5.0 parts of emulsifier and 0.05-5.0 parts of catalyst; the number of hydroxyl groups of the polyether polyol is more than 3, and the hydroxyl value of the polyether polyol is 22-56 mg KOH / g; The curing agent includes diisocyanate; The molar ratio of the hydroxyl group in the premix to the isocyanate group in the curing agent is 1: 1 to 1.1; The layer plate includes one or more layers of a steel plate, an aluminum alloy plate, an engineering plastic plate and a fiber plate; The method for preparing the energy-absorbing and anti-collision material comprises the following steps: The energy absorbing and anti-collision material is obtained by pouring the raw materials for preparing the polyurethane energy absorbing layer on the layers or between the layers, and performing foaming and cross-linking integrated molding.

2. The energy-absorbing and anti-collision material according to claim 1, characterized in that: The thickness of the polyurethane energy absorbing layer is 1-20 mm.

3. The energy-absorbing and anti-collision material according to claim 1, characterized in that: The thickness of the steel plate is 0.5-3 mm.

4. The energy-absorbing and anti-collision material according to claim 1, characterized in that: The thickness of the aluminum alloy plate is 0.5-3 mm.

5. The energy-absorbing and anti-collision material according to claim 1, characterized in that: The material of the fiberboard includes one or more of polyethylene fiber, Kevlar fiber, carbon fiber, basalt fiber and polyester fiber, and the thickness of the fiberboard is 0.5-5 mm.

6. The energy absorbing and anti-collision material according to claim 1, characterized in that: The material of the engineering plastic plate includes one or more of polyphenylene ether, nylon, microporous foamed polypropylene, polyoxymethylene and polyimide, and the thickness of the engineering plastic plate is 0.5-5 mm.

7. The energy absorbing and anti-collision material according to claim 1, characterized in that: The polyurethane energy absorbing layer and the layer plate are alternately stacked, and the total number of the alternately stacked layers is 2 to 7 layers.

8. The energy absorbing and anti-collision material according to claim 1 or 7, characterized in that: The energy-absorbing and anti-collision material comprises an aluminum alloy plate, a polyurethane energy-absorbing layer and a steel plate stacked in sequence, or comprises an aluminum alloy plate, a first polyurethane energy-absorbing layer, a steel plate and a second polyurethane energy-absorbing layer stacked in sequence, or comprises an aluminum alloy plate, a first polyurethane energy-absorbing layer, a fiberboard, a second polyurethane energy-absorbing layer and a steel plate stacked in sequence.

9. The method for preparing the energy-absorbing and anti-collision material according to any one of claims 1 to 8, characterized in that: The following steps are involved: The energy absorbing and anti-collision material is obtained by pouring the raw materials for preparing the polyurethane energy absorbing layer on the layers or between the layers, and performing foaming and cross-linking integrated molding.

10. The preparation method according to claim 9, characterized in that: The temperature of the foaming and cross-linking integrated molding is 35-80° C., and the time is 2-10 minutes.

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